Problem (for me) is that this was not really built using Tableau's built-in mapping tools... getting this to work on a production level, and without Allan jumping in to help, is very difficult in my experience.
Valid point. Still a great example of what is possible.
The polygon/dual axis was all Tableau.
Not how I would have done it, but it doesn't mean to say it can't be done.
The "trick" with polygons and points is the same for any Tableau mapping:
Remember Joe Mako's advice: Tableau mapping is just a scatterplot.
With that in mind, you need to think about what you're analysing: I always recommend analysing at the lowest level of detail: in this case, it wasn't schools, it was students (i.e. who is going to be affected by proposed changes).
So to do a dual-axis (i.e. areas, which are joined up dots in a specific order) + dots of the unit of analysis: (how? on the school they attend? = left outer join on school).
So your dataset needs every point of the polygon (i.e. the area of the school boundary), with the features (i.e. the school name) + all the points you want to plot for the pupils.
The reason I don't advocate this is that it makes the datasets huge, slow to render etc.
Much better making shapefiles (that don't change much over time): in this case, current and proposed. Layer them with your background map layer, and then present those via Geoserver/WMS to Tableau, and then concentrate on the foreground analysis. If you need to calculate how many objects are in a certain area, then it's a matter of a calculated field over the join; you don't need to "show" that in the view; a simple bar chart would do just fine.
Here's a blog post for those that haven't read it.
I'm not going to argue. Best of luck to all who attempt this.
I agree. It's not trivial, but should be.
I would have liked to have seen this kind of work done at the Advanced Mapping Training session.
Thinking about it, if I get time; I will do a set of tutorials.
The issue is I'd be doing it "my way" - this might not be fit for everyone's purpose.
The other thing is I'm mega busy with work stuff/prepping for TCC2014.
Has someone taken over your old site, allan.walker.0? Your link above is broken (http://theywalkedtogether.blogspot.com/2014/01/tableaumapping-guest-blog-post-from.html).
Someone on the G+ Higher Ed Tableau community was asking about your school district file today, and I was hoping to point them at your prior work.